Electrochemical device

ABSTRACT

An electrochemical device has at least one carrier substrate ( 1 ) provided with a stack ( 2 ) of functional layers, including at least one electrochemically active layer ( 4 ), which is capable of reversibly and simultaneously inserting ions and electrons and is arranged between two electroconductive layers. The device can be of the electrochromic type. The functionality of at least one of the functional layers, with the exception of one of the electroconductive layers ( 3,8 ), is locally inhibited so as to delimit inactive peripheral or non-peripheral regions in the stack ( 2 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of electrochemical deviceshaving at least one electrochemically active layer capable of reversiblyand simultaneously inserting ions and electrons, in particularelectrochromic devices. These electro-chemical devices are, inparticular, used to manufacture windows whose optical and/or energytransmission or optical reflection can be modulated using an electriccurrent. They can also be used to manufacture energy-storage elementssuch as batteries or, alternatively, gas sensors or display elements.

2. Description of the Background

Considering the particular example of electrochromic systems, it will berecalled that, as is known, they include a layer of a material capableof reversibly and simultaneously inserting ions, in particular cations,and electrons, and whose oxidation states corresponding to the insertedand deinserted states are of distinct coloration, one of the statesgenerally being transparent. The insertion or deinsertion reaction iscontrolled by a suitable electrical power supply, in particular byapplying an appropriate potential difference. The electrochromicmaterial, in general based on tungsten oxide, thus needs to be broughtinto contact with a source of electrons, such as a transparentelectroconductive layer, and a source of ions, such as anionic-conductor electrolyte.

It is furthermore known that, in order to provide at least of the orderof a hundred switching operations, a back electrode which is itself alsocapable of reversibly inserting cations, symmetrically with respect tothe layer of electrochromic material, must be associated with the layerof electrochromic material, so that, macroscopically, the electrolyteappears as a simple ion medium.

The back electrode must be formed either by a layer which has neutralcoloration, or one which is at least transparent when the electrochromiclayer is in the uncoloured state. Since tungsten oxide is a cathodicelectrochromic material, that is to say its coloured state correspondsto the most reduced state, an anodic electrochromic material such asnickel oxide, iridium oxide or vanadium oxide, without implying anylimitation, is generally used for the back electrode. It has also beenproposed to use a material which is optically neutral in the oxidationstates in question, for example cerium oxide or organic materials suchas electronic conducting polymers (polyaniline, etc.) or Prussian blue.

Such systems are described, for example, in European PatentsEP-0,338,876, EP-0,408,427, EP-0,575,207 and EP-0,628,849.

These systems can currently be divided into two categories, according tothe type of electrolyte which they use:

either the electrolyte is present in the form of a polymer or a gel, forexample a protonic-conduction polymer such as those described inEuropean Patents EP-0,253,713 and EP-0,670,346, or a polymer withlithium-ion conduction such as those described in Patents EP-0,382,623,EP-0,518,754 or EP-0,532,408

or the electrolyte is an inorganic layer which is an ionic conductor butelectronically insulating, in which case the term “all solid”electrochromic systems is used.

Reference may be made to patents EP97/400702.3 of Mar. 27, 1997 and EP-0831 360 for the description of an “all solid” system. It is principallyto this type of system that the invention relates, because it has aclear advantage in terms of ease of manufacture. This is because, withsuch a configuration, all the layers of the system can be depositedsuccessively on a single carrier substrate (whereas in the system inwhich the electrolyte is a polymer or a gel, it is normally necessary tomanufacture two “half-cells” which are assembled together via theelectrolyte, which actually requires the use of two carrier substratesand the running of two series of layer depositions in parallel on eachof them).

Whatever the configuration adopted, one requirement with this type ofelectrochemical system consists in giving it a “memory effect” which issufficient in terms of the application in question. This term isintended to mean the capacity which the system has to stay in a givenstate once the electrical power supply has been cut. In the case of anelectrochromic window, this state is generally its coloured state. Inthe absence of an electrical power supply, it tends to revert to itsuncoloured state. The aim is clearly for this memory effect to be ableto last as long as possible so that, by means of the electrical powersupply of the system, the user can actually control its statesatisfactorily. In practice, it is for example desirable for theelectrochromic window to be able to stay in the coloured state, with thepower off, for several hours, for example 10 to 20 hours.

In practice, this goal is difficult to achieve because the system has todeal with a leakage current from one electroconductive layer to theother, in particular at the periphery of the system, which tends to makeit revert to its equilibrium state, that is to say to its uncolouredstate.

A first solution consisted in accepting the existence of these leakagecurrents, and in re-supplying the system with electricity when it is inits coloured state, with a given periodicity, in order to compensate forthem. It is not, however, fully satisfactory, if only because theseleakage currents can vary from one window to another, and in this casethe coloration achieved by two similar windows supplied with electricityin the same way is different.

A second solution consisted in putting a margin on one of the twoelectroconductive layers, that is to say depositing the layers in such away that they are offset at their periphery, and thus ineliminating/reducing the leakage current from one layer to another attheir respective peripheries. The solution is effective but makes theprocess of manufacturing the system more complicated: in particular, itmakes it necessary to deposit at least one of the two electroconductivelayers by using a mask on the carrier substrate.

SUMMARY OF THE INVENTION

The object of the invention is therefore to overcome these drawbacks byproviding, in particular, a novel method of processing theelectrochemical devices described above in order to improve theirperformance, very particularly in order to limit/eliminate the risks ofshort-circuits, the so-called leakage currents and, thereby, in order toincrease their “memory effect”, and to do so while favouring simplicityin its implementation.

The invention firstly relates to a method of processing anelectrochemical device having at least one carrier substrate providedwith a stack of functional layers comprising at least oneelectrochemically active layer which is capable of reversibly andsimultaneously inserting ions and electrons and which is arrangedbetween two electroconductive layers. It is, in particular, anelectrochemical device of the electrochromic type, with a stack offunctional layers including at least, successively:

a first electroconductive layer,

a first electrochemically active layer capable of reversibly insertingions, for example cations such as H⁺, Li⁺ or anions such as OH⁻, inparticular of an anodic (or cathodic, respectively) electrochromicmaterial,

an electrolyte layer,

a second electrochromically active layer capable of reversibly insertingthe said ions, in particular of a cathodic (or anodic, respectively)electrochromic material,

a second electroconductive layer.

The method of the invention is characterized in that the functionalityof at least one of the functional layers, with the exception of one ofthe electroconductive layers, in particular with the exception of thefirst (the one closest to the carrier substrate), is locally inhibitedso as to delimit an inactive peripheral region in the stack.

In the context of the invention, the term “layer” is intended to meaneither unitary layers or the superposition of a plurality of layerswhich jointly fulfil the same function. This is, in particular, the casewith the electrolyte layer, which may consist of two or three superposedlayers, as disclosed for example by the aforementioned patentEP97/400702.3.

Still in the context of the invention, the stack of layers may alsocomprise other layers, in particular protective layers, barrier layers,or layers with an optical or bonding function.

The benefit of the invention resides in the simplicity of itsimplementation, further to its effectiveness. This is because the methodallows the layers to be processed once they are (all) deposited in astandardized way, without having to carry out selective deposition oflayers, with mask systems or the like in order to obtain a “margin” oran offset, for example. The invention is therefore particularlybeneficial in the case of stacks of functional layers containing onlylayers of solid material: (the “all solid” systems mentioned above).

In the context of the invention, the term “solid” material is intendedto mean any material having the mechanical strength of a solid, inparticular any material which is essentially inorganic or hybrid, thatis to say partially inorganic and partially organic, such as thematerials which can be obtained using a process of deposition by sol-gelsynthesis.

In fact, in particular in the case of such an all-solid system, all ofthe layers can be deposited one after the other on the carriersubstrate, preferably with the same deposition technique, on the sameproduction line (in particular deposition by magnetic field-assistedsputtering), then all of the stack apart one of the electroconductivelayers can be processed according to the invention. Of course, theinvention also comprises the alternative variant consisting in stoppingthe deposition process, and in processing only some of the stack alreadydeposited, then in continuing the deposition of the “missing” layers inorder to form the “full” stack. (In the case of a system which is not“all solid”, the “missing” layers may be added by assembling thesubstrate with a second substrate, itself functionalized appropriately).

Keeping one of the electroconductive layers intact, unaffected by theinhibition process according to the invention, makes it possible toensure correct supply of electricity to the terminals of the device.There are a variety of possible ways of maintaining this integrity forthem, and these will be explained below.

The object of this local “inhibition” of the stack of functional layersis to deactivate the device at its periphery, over a border a fewmillimetres wide, for example, so that in this periphery the systemremains permanently in its least ionically and/or electronicallyconducting state (uncoloured state for most electrochromic systems).This “inactive” border is not in itself disadvantageous because itsdimensions can be controlled and it can thus be concealed with ease, ifthis is deemed necessary from an aesthetic point of view, by thefitting, framing and peripheral-seal system of the device which isalways present, very particularly when it is an electrochromic window.

This border actually equates to intentionally cutting the electricalcircuit at the periphery of the system, thus eliminating any risk ofshort-circuit due to the current flowing between the twoelectroconductive layers. In the extreme, the electrical circuit may becut by inhibiting only one of the electrochemically active layersexhibiting reversible insertion and/or the electrolyte layer and/or oneof the electroconductive layers at their peripheries. However, asmentioned above, it is simpler to process all of the stack apart fromthe first layer. It should be noted that short-circuits are, inparticular, due either to direct contact between the twoelectroconductive layers, or indirectly via one of the electrochemicallyactive layers when these turn out also to be electronic conductors inone of their states (inserted or uninserted). Thus, tungsten oxide is abetter electronic conductor in its coloured state, the same being trueof nickel oxide and iridium oxide.

The invention provides two main variants for obtaining thislocalized-inhibition effect.

The first variant consists in locally inhibiting the functionality of atleast one of the layers by cutting it (them) over its (their)thickness(es) along a closed line making it possible to delimit theinactive region of the stack between the said closed line of theedge/side of the stack (assuming all of the stacks, or the majority ofthem, have similar dimensions and/or are exactly superposed on oneanother. In fact, the first electroconductive layer usually has slightlylarger dimensions than all the others, in order to make it easier toelectrically connect it to the second layer, which allows the requiredconnection elements to be placed on its surface which “protrudes” fromthe stack.

This cut makes it possible to obtain a groove which breaks the circuitas explained above and leaves the periphery of the device unpowered.

Preferably, the cut is made along a closed line which, in smallerproportions, has a profile similar or identical to that of the edge ofthe stack (or of the edge of the first layer which experiences thecutting, if the underlying layers are of slightly different dimensions,in particular the first as indicated above). This provides an inactiveborder which “follows” the perimeter of the device and is easy to hide.

Advantageously, the cut is made by some mechanical means, in particulara cutting means, or by laser irradiation. One embodiment consists inleaving the device stationary during the processing and in fitting themechanical means/laser emitter on a moving part, and another embodimentconsists in doing the opposite.

Other means may also be used for making the cut by abrasion. Forexample, a means emitting a jet of gas or liquid under pressure(nitrogen, air), or a means emitting abrasive particles (glass orcorundum beads, shot, solid CO₂ beads, etc.).

This cutting operation may be carried out equally well whether thesystem is in the coloured or uncoloured state. When it is carried outusing a laser beam, it may be beneficial to choose a coloured state, inorder to increase the laser absorption by the stack at the wavelengthused.

The second variant consists in locally inhibiting the functionality ofat least one of the layers of the stack (always with the exception ofone of the electroconductive layers) by degrading it (them) at its(their) periphery(ies), in particular by a suitable heat treatment or bysuitable laser irradiation.

In this figurative case, the degradation is preferably carried out notalong a closed line, like the cut according to the first variant, butover the entire surface of the peripheral border which it is desired to“deactivate” thus.

Heat treatment or laser treatment have proved very effective inmodifying the layer(s) in question sufficiently in terms of theirchemical composition or their structure, in order thus to make theminactive. This is degradation in all likelihood involving, for example,dehydration and/or structural modification (in particular bycrystallization) of the layer in question at least partially, withouteliminating it.

It is rather beneficial to carry out this degradation treatment on thestack of layers when it is in its uncoloured state: this is because itis in this state that layers of the electrochromic type are leastelectronically conducting.

It can be seen that irradiation with a laser light can be used either inthe context of the first variant, causing actual localized ablation, orin the context of the second variant, doing no more than modifying it.Their accuracy and their effectiveness make lasers particularlybeneficial, it then being sufficient to modulate their operatingparameters, as will be explained in detail below.

It is thus possible, in the scope of the invention, to make a pluralityof closed peripheral cut lines, each closed line having a parametersmaller than the one which is adjacent to it and closer to the edge ofthe stack than it, and being contained in the “interior” area of thestack delimited by it (the successive closed lines may thus beconcentric).

The same is true regarding the variant in which degradation is carriedout: it is possible to make not one peripheral degraded region butseveral, for example concentric ones which may or may not be separatedfrom one another by an unprocessed stack portion.

It should be noted that the two variants described above are alternativeor cumulative. It is thus possible, in particular, to make a peripheralcut line and furthermore degrade the region which lies between the saidline and the edge of the stack.

Moreover, it is also possible according to the invention to locallyinhibit the functionality of at least one of the functional layers, withthe exception of one of the electroconductive layers, so as to delimitan“inactive contours” or a non-peripheral “inactive region” in the device.

This inhibition may be carried out using one or other of the twovariants explained above, namely either by localized degradation orlocalized ablation of the layer or layers in question, using the samemeans, namely heat treatment, laser treatment or some cutting means.

This operation may have two different purposes. It may firstly make itpossible to reduce/eliminate non-peripheral short-circuits in the stackwhen the device is in operation, by deactivating the regions where pointdefects lead to electrical contacts between the two electroconductivelayers, the regions thus rendered inactive being very small andtherefore not very or not at all noticeable. In order to make theseregions even less noticeable, arrangements may be made, once the regionshave been processed, to colour them permanently using an ink jet of adark colour close to that of the system in the coloured state. The“corrected” regions are therefore completely masked when the system isin the coloured state (the state in which points remaining bright wouldbe most noticeable). It is thus possible easily and effectively tocorrect the point defects of the system.

This operation may also make it possible to draw patterns in the device,these patterns appearing only when the system is in its coloured state.It is thus possible, according to the way in which the degradation orablation is carried out, to obtain patterns which are “solid” ordelimited by contours as desired.

It has been seen above that the preferred embodiment of the inventionconsisted in the processing method affecting all of the functionallayers apart from the (first) electroconductive layer. In order topreserve the latter's integrity, its deposition parameters mayadvantageously be selected in order to make it more resistant, harderand denser than the other layers and, in particular, than the otherelectroconductive layer. The characteristics of the layer are thusmodulated in combination with those of the means used for the processingso that the layer is not modified.

If this layer is, for example, deposited by magnetic field-assistedsputtering, it is possible, in a known way, to modulate its density byvarying the pressure in the deposition chamber, the depositiontemperature, etc.

It is thus possible to vary the deposition techniques used. For example,the layer which it is desired to preserve may be deposited by a hotdeposition technique of the pyrolysis type (in the solid, liquid or gasCVD phase), well-suited to obtaining doped metal oxide layers and knownto make it possible to obtain particularly hard and resistant layers,and depositing some or all of the other layers by a deposition techniquewhich does not generally make it possible to achieve such highhardnesses, such as a vacuum deposition technique (sputtering,evaporation).

The invention also relates to the electrochemical device of theelectrochromic type processed using the method described above, whichhas at least one peripheral inactive region remaining permanently in theuncoloured state, in particular in the form of a margin with a width of,for example, at most 5 mm.

The device processed according to the invention preferably has, duringoperation (in the coloured state), a leakage current (total leakagecurrent per unit length of the perimeter) less than or equal to 20μA/cm, in particular less than or equal to 10 μA/cm or 5 μA/cm.

BRIEF DESCRIPTION OF THE DRAWINGS

Other details and advantageous characteristics of the invention will befound in the following description of a nonlimiting embodiment withreference to the appended drawing, in which:

FIG. 1: represents an electrochromic window in section.

This figure is extremely schematic and does not respect the proportionsbetween the various elements represented, this being in order to make itmore readable. In particular, all the electrical connections known perse are furthermore not represented.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

The example described below relates to an electrochromic window of the“all solid” type according to the teaching of patents EP97/400702.3 andEP-0,831,360 which were mentioned above. The invention is not, however,limited to such a configuration.

Thus, as mentioned above, the invention can be applied to any type ofelectrochemical systems, in particular electrocontrollable windows ofthe electrochromic window type. It is preferably in the form of a stackof functional layers comprising, in succession, a preferably transparentelectroconductive layer, a so-called cathodic electrochromic layercapable of reversibly inserting ions such as H⁺, Li⁺, Na⁻, Ag⁺ or OH⁻,an electrolyte layer, optionally a back electrode in the form of asecond so-called anodic electrochromic layer, also capable of reversiblyinserting the said ions, and lastly a second electroconductive layer.

As regards the nature of the electroconductive layers of the device,there are two possible variants: materials based on doped metal oxide,such as fluorine-doped tin oxide SnO₂:F or tin-doped indium oxide ITOmay be employed. It is also possible to use layers of metal or metalalloy, for example from gold Au, silver Ag or aluminium Al. Since thedevice generally has two electroconductive layers, they may either bothbe metallic or both be based on doped oxide, or one based on metal andthe other based on doped oxide. They may furthermore be made up ofsuperposed conductive layers, for example at least one metallic layercombined with a doped metal oxide layer.

In order to form the layer of cathodic electrochromic material, amaterial or a mixture of materials which is or are chosen from the groupcomprising tungsten oxide WO₃, molybdenum oxide MoO₃, vanadium oxideV₂O₅, niobium oxide Nb₂O₅, titanium oxide TiO₂, a “cermet” material(combination of metallic material and ceramic, in particular in the formof metal particles in a ceramic matrix) such as WO₃/Au or WO₃/Ag, amixture of tungsten and rhenium oxides WO₃/ReO₃ may be chosen. Thesematerials are suitable, in particular, in the case of reversibleinsertion of lithium ions. In the case when the device operates byreversible insertion of protons, the same materials may be used, butthis time hydrated.

In order to form the layer of anodic electrochromic material, a materialwhich corresponds to the formula M_(x)A_(y)U_(z), with M a transitionmetal, A the ion used for the reversible insertion, for example analkali metal or a proton, and U a chalcogen such as oxygen or sulphur,may be chosen.

It may be, particularly in the case of inserting proton ions H⁺, acompound or a mixture of compounds belonging to the group comprisingLiNiO_(x), IrO_(x)H_(y), IrO_(x)H_(y)N_(z), NiO_(x), NiO_(x)H_(y)N_(z),RhO_(x), CoO_(x), MnO_(x), RuO_(x). In the case of reversible insertionof lithium ions Li⁺, a compound or a mixture of compounds belonging tothe group comprising LiNiO_(x), LiMn₂O₄, IrO_(x), Li_(x)IrO_(y),Li_(x)S_(n)O_(y), NiO_(x), CeO_(x), TiO_(x), CeO_(x)—TiO_(x), RhO_(x),CoO_(x), CrO_(x), MnO_(x) will rather be chosen.

As regards the choice of the electrolyte material, there are in fact twotypes of it as mentioned above.

In the context of the invention, electrolytes in the form of solidmaterial are favoured, in particular based on metal oxide, preferablycomprising a layer of an ionic conductor material which is capable ofreversibly inserting the ions but whose degree of oxidation is keptessentially constant, such as a material with electrochromic propertiesof the WO₃ type, as described in patent EP97/400702.3. The inventiondoes, however, include the other types of electrolyte (polymer, gel,etc.).

The functional system of the element according to the invention maytherefore be arranged either between two substrates or on a singlesubstrate, more particularly in the case of an “all solid” system. Therigid carrier substrates are preferably made of glass, acrylic orallylic polymer, polycarbonate or certain polyurethanes. The carriersubstrates may also be supple and flexible and intended to be laminatedto rigid substrates, and this may involve flexible polycarbonate,polyethylene terephthalate (PET) etc. The lamination may be carried outwith intermediate polymer sheets of the thermoplastic type such aspolyvinylbutyral (PVB), ethylene vinyl acetate (EVA) or certainpolyurethanes.

These windows may thus have a “monolithic” structure, that is to saywith a single rigid substrate, or with a plurality of rigid substrates,have a laminated and/or multi-pane structure, or alternatively aso-called asymmetric window structure with an outer plastic layer, inparticular based on polyurethane with energy-absorption properties,which structure is in particular described in patents EP-191,666,EP-190,953, EP-241,337, EP-344,045, EP-402,212, EP-430,769 andEP-676,757.

Let us now return to the specific example of an electrochromic windowprocessed according to the invention, which is represented in FIG. 1.

All the layers are based on metal oxide(s) and are deposited by magneticfield-assisted reactive DC sputtering (in an Ar/O₂ or Ar/H₂/O₂atmosphere from suitable metal targets).

FIG. 1 represents a clear silica-soda-lime glass substrate 1 with anarea of 1000 cm² and a thickness of 3 mm, on top of which there is the“all solid” electrochromic system made up of the following layer stack2:

a first tin-doped indium oxide ITO electroconductive layer 3 with athickness of 150 nm,

a first layer 4 of anodic electrochromic material, made of hydratediridium oxide H_(x)IrO_(y) with a thickness of 37 nm,

an electrolyte bi-layer made up of a tungsten oxide WO₃ layer 5 with athickness of 200 nm then a 200 nm tantalum oxide layer 6,

a second layer 7 of cathodic electrochromic material, made of hydratedtungsten oxide H_(x)WO₃ with a thickness of 380 nm,

a second ITO electroconductive layer 8 with a thickness of 280 nm.

The electroconductive layer 3 was deposited with different depositionconditions from those used for the other electroconductive layer 8, sothat the first is significantly denser and harder than the second which,by comparison, appears more “porous”. This guarantees that the firstlayer will not be affected by the processing according to the invention.

One variant consists in slightly modifying the thicknesses of theexample described above, using a 100 nm WO₃ layer 5, a 100 nm tantalumoxide layer 6, a 280 nm H_(x)WO₃ layer 7 and finally a 270 nm ITO layer8.

Twelve identical specimens were made in this way, in order to make itpossible to evaluate statistically the effectiveness of the processingaccording to the invention, which consisted in making a groove/cut onall the layers except for the first, using a suitable laser beam.

The types of laser which can be used to make this cut (as well as,alternatively, to carry out controlled degradation without ablation) arein particular of the pulsed EXCIMER laser type (using KrF with awavelength of 248 nm, TeCl with a wavelength of 308 nm, ArF with awavelength of 193 nm, XeF with a wavelength of 351 nm or F2 with awavelength of 157 nm), or a DC diode laser (wavelength 532, 510, 578or808 nm) or a “YAG” (yttrium aluminium garnet Y₃Al₅O₁₂ crystal) laserwith a wavelength of 1 μm, or a CO₂ laser with a wavelength of 9.3 and10.6 μm. The choice of the laser depends, in particular, on theabsorption spectrum of the stack of layers. In order to control itappropriately (in particular in order to choose between actual ablationor only degradation of the layer(s) in question, a variety of parametersneed to be adjusted and taken into account, in particular the fluence onthe substrate (in J/cm²), the frequency of the laser (in Hz), the speedat which the laser emitter moves relative to the substrate (mm/s), thenumber of pulses received at a point on the layer, and the width of thecut (in mm).

In the present case, a KrF EXCIMER laser was used, with a laser beamhaving an energy density of 0.12 J/cm², fitted on a part moving over thestack so as to make a groove 9 which has a width of about 100 μm andwhich follows the contour of the stack 2 at a distance of about 2 mmfrom its edge, that is to say a substantially square groove. The termcontour of the stack is intended here to mean that of all the functionallayers apart from the first, which has slightly larger dimensions inorder to make it easier to fit the connection elements, in a known way.

It was then observed, once the stack had been processed in this way andthe electrical connections had been made, that the peripheralshort-circuits encountered in the coloured state are of extremely lowlevel and are extremely reproducible from one specimen to another (itshould be noted that this assessment is made with reference to thecoloured state of the electrochromic system, because this is the mostunfavourable one: the reason for this is that, in this case, the activeelectrochromic layers made of iridium oxide, 4, and of H_(x)WO₃, 7, aregood ionic, and also good electronic, conductors).

The leakage currents measured are thus on average 4 μA/cm, whileidentical specimens which were not processed have leakage currents ofthe order of 300 to 400 μA/cm. (These comparative specimens, which arenot processed according to the invention, are provided with margins sothat the two electroconductive layers are offset relative to oneanother: before deposition, the edges are masked with 50 to 100 μm-thickadhesive tape, which is removed after deposition in order to take themeasurements).

Tests were then carried out in order to assess the effect of thissubstantial elimination of the peripheral leakage currents on the memoryeffect of the system.

In the uncoloured state (reference), its optical transmission T_(L)(based on the D₆₅ illuminant) is 65%. In the maximum-coloured state(reference), its T_(L) is 13.2%.

Once it has been put in its covered state by applying an appropriatevoltage, the electrical circuit is open:

after 2 hours, the T_(L) is 14.5%,

after 17 hours, the T_(L) is 20.5%,

after 27 hours, the T_(L) is 23.6%

(test carried out on 12 specimens, the values of T_(L) being averaged).

This means that, after a full day, the system is still significantlycoloured, with a great improvement over unprocessed systems.

It should be clear that the device on which the laser processing hasbeen carried out, which is represented in FIG. 1, is generally“incomplete” insofar as it generally needs to be provided with a meansof protection on top of the stack 2, for example by laminating it withglass or a flexible substrate such as PET, to produce a double-glazingassembly in which the stack faces the intermediate gas layer and mayoptionally be provided with a protective film. The stack may also beencapsulated with a leaktight polymer/varnish such as a polyurethane orepoxy varnish, or a polyparaxylylene film, or an inorganic layer such asSiO₂ or Si₃N₄, or any other inorganic or organo-mineral layer obtained,in particular, by a sol-gel process.

The 2 mm uncoloured band 10 on the perimeter of the stack which is dueto the laser processing is easy to conceal when fitting the window.

The method according to the invention is therefore efficient and avoidshaving to interrupt the sequence of layer deposition for forming thestack.

What is claimed is:
 1. An electrochemical device having at least onecarrier substrate in contact with a stack of functional layerscomprising two electroconductive layers and at least oneelectrochemically active layer, which is capable of reversibly andsimultaneously inserting ions and which is arranged between the twoelectroconductive layers, wherein at least one of the functional layers,with the exception of one of the two electroconductive layers, comprisesan active region, and a deactivated peripheral region, where the activeregion is surrounded by the deactivated peripheral region; and thedeactivated peripheral region has a higher electrical resistivity thanthe active region.
 2. The device according to claim 1, wherein thedeactivated peripheral region of the at least one of the functionallayers is electrically isolated from the active region.
 3. The deviceaccording to claim 2, wherein the device further comprises a groove; andthe groove separates the active region of the at least one of thefunctional layers from the deactivated peripheral region.
 4. The deviceaccording to claim 1, wherein the deactivated peripheral regioncomprises a structurally modified portion of the at least one of thefunctional layers.
 5. The device according to claim 4, wherein thestructurally modified portion of the at least one of the functionallayers comprises a dehydrated or crystallized portion of the at leastone of the functional layers.
 6. The device according to claim 4,wherein the structurally modified portion of the at least one of thefunctional layers is produced by heating or laser irradiating the atleast one of the functional layers.
 7. The device according to claim 1,wherein the stack comprises at least, successively, a firstelectroconductive layer, an electrochemically active layer capable ofreversibly inserting ions in an anodic or cathodic electrochromicmaterial, an electrolyte layer, a second electrochemically active layercapable of reversibly inserting the ions in the cathodic or anodicelectrochromic material, and a second electroconductive layer.
 8. Thedevice according to claim 1, wherein the stack of functional layerscontains only layers of solid material.
 9. The device according to claim1, wherein the two electroconductive layers include a firstelectroconductive layer more resistant, harder and/or denser than thefunctional layers; and each of the functional layers, apart from thefirst electroconductive layer, includes a different active regionsurrounded by a different deactivated peripheral region.
 10. The deviceaccording to claim 1, wherein the device has at least one peripheralinactive region remaining permanently in an uncolored state.
 11. Thedevice according to claim 1, wherein during operation the device has aleakage current less than or equal to 20 μA/cm.
 12. An electrochemicaldevice having at least one carrier substrate in contact with a stack offunctional layers comprising two electroconductive layers and at leastone electrochemically active layer, which is capable of reversibly andsimultaneously inserting ions and which is arranged between the twoelectroconductive layers, wherein at least one of the functional layers,with the exception of one of the two electroconductive layers, comprisesat least one deactivated non-peripheral region surrounded by an activeregion.
 13. The device according to claim 12, wherein the deactivatednon-peripheral region of the at least one of the functional layers iselectrically isolated from the active region.
 14. The device accordingto claim 12, wherein the deactivated non-peripheral region has a higherelectrical resistivity than the active region.
 15. The device accordingto claim 14, wherein the deactivated peripheral region comprises astructurally modified portion of the at least one of the functionallayers.
 16. The device according to claim 15, wherein the structurallymodified portion of the at least one of the functional layers comprisesa dehydrated or crystallized portion of the at least one of thefunctional layers.
 17. The device according to claim 15, wherein thestructurally modified portion of the at least one of the functionallayers is produced by heating or laser irradiating the at least one ofthe functional layers.
 18. The device according to claim 12, wherein thedeactivated non-peripheral region forms a pattern in the device.
 19. Thedevice according to claim 12, wherein the two electroconductive layersinclude a first electroconductive layer more resistant, harder and/ordenser than the functional layers; and each of the functional layers,apart from the first electroconductive layer, includes a differentdeactivated non-peripheral region surrounded by a different activeregion.
 20. An electrochemical device having at least one carriersubstrate in contact with a stack of functional layers comprising twoelectroconductive layers and at least one electrochemically activelayer, which is capable of reversibly and simultaneously inserting ionsand which is arranged between the two electroconductive layers, whereina first at least one of the functional layers, excluding one of the twoelectroconductive layers, comprises a first active region surrounded bya first deactivated peripheral region; and a second at least one of thefunctional layers, excluding the one of the two electroconductivelayers, comprises at least one second deactivated non-peripheral regionsurrounded by a second active region.
 21. The device according to claim20, wherein the first deactivated peripheral region is electricallyisolated from the first active region; and the at least one seconddeactivated non-peripheral region is electrically isolated from thesecond active region.
 22. The device according to claim 20, wherein thefirst deactivated peripheral region has a higher electrical resistivitythan the first active region; and the second deactivated non-peripheralregion has a higher electrical resistivity than the second activeregion.
 23. The device according to claim 20, wherein the twoelectroconductive layers include a first electroconductive layer moreresistant, harder and/or denser than the other functional layers; andeach of the functional layers, apart from the first electroconductivelayer, includes a different active region surrounding a differentdeactivated non-peripheral region and surrounded by a differentdeactivated peripheral region.
 24. An electrochemical device processedusing the method of claim 20, wherein during operation the device has aleakage current less than or equal to 20 μA/cm.